Dispersive Mixing in Multicomponent Multiphase Flow: Numerical and Physical Effects

将工业排放的二氧化碳注入枯竭的油藏和深层盐水含水层是对抗全球变暖的一种可行方法。英国有潜力在开发二氧化碳捕获和储存技术方面处于领先地位，因为北海有巨大的油藏储存能力。此外，维持目前的油气产量水平对英国的能源安全至关重要，而二氧化碳注入是提高北海石油采收率的一种行之有效的方法。向油藏注入二氧化碳通常会导致水、油、气流体相同时流过多孔储层岩石。相行为和流动之间的相互作用决定了额外采收率和二氧化碳储存效率。为了确保现有的数学模型和用于近似它们的模拟器是正确的，迫切需要发展对多相地下流的基本物理的理解。对于在三相之间划分的组分的位移，可以用解析解来求解，但尚不清楚它们是否模拟了真正的物理位移，其中包括分子扩散和毛细压力的分散效应。模拟位移对数值色散的敏感性（数值误差，像物理色散一样，倾向于涂抹流体成分中的尖锐锋面）不能简单地从等效两相位移的敏感性确定。本项目将首次在基础水平上严谨地研究多组分多相流中的色散效应。本项目的目标是推导出多组分多相流的物理正确的分散模型，并在基于流线的三维油藏模拟器中实现它们。当该项目完成后，该模拟器将用于设计高效的二氧化碳储存和提高石油采收率的项目，并具有更高的确定性，即储存的二氧化碳将在地质时间内保留在油藏中。

Injection of carbon-dioxide (CO2) emissions from industrial sources into depleted oil reservoirs and deep saline aquifers is one viable way to combat global warming. The U.K. has the potential to take the lead in developing technologies for CO2 capture and storage because of the vast storage capacity of oil reservoirs in the North Sea. Moreover, maintaining current levels of hydrocarbon production is critical to U.K. energy security and CO2 injection is a proven method for increasing oil recovery in the North Sea.CO2 injection into oil reservoirs typically results in water, oil and gas fluid phases simultaneously flowing through porous reservoir rocks. Interaction between phase behaviour and flow determines the amount of additional oil recovered and CO2 storage efficiency. There is a critical need to develop an understanding of the fundamental physics in multiphase subsurface flow in order to ensure that existing mathematical models and the simulators used to approximate them are correct. Analytical solutions for displacements with components that partition between three phases are available, but it is not clear whether they model the true physical displacement which includes the dispersive effects of molecular diffusion and capillary pressure. The sensitivity of simulated displacements to numerical dispersion (numerical errors that, like physical dispersion, tend to smear sharp fronts in fluid composition) cannot be simply determined from the sensitivity for equivalent two-phase displacements.This project will be the first to rigorously study dispersive effects in multicomponent multiphase flow at a fundamental level. The goals of this project are to derive physically correct dispersion models for multicomponent multiphase flow and to implement them in a three-dimensional streamline-based reservoir simulator. When this project is completed, the simulator will be used to design efficient CO2 storage and enhanced oil recovery projects with a higher-degree of certainty that stored CO2 will remain in oil reservoirs for geologic time.